# What does a perception check really signify? Can they be repeated?

When a character makes a perception check, does fail indicate whether they permanently fail to see what is hidden, or just that they need to try again? So far our DM has let us repeat perception checks, but it just seems weird, as the DC now only indicates the amount of time necessary to perceive something, and the other members of my groups sometimes keep making checks until they get a 20. Obviously, this is really boring for me.

Can perception checks on the same thing be repeated? What does a failure at a perception check really mean happened (temporary failure vs. permanent failure)?

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This is how I play it. This is 4e, but maybe heavily modified to my taste and not the "proper" way.

Perception to notice something new

In this case, I'd say just one roll. If the DM think it's something that somebody needs to find out, he may give you a second opportunity to pick it up (e.g. nobody notices the thieves' guild tattoo on the wrist of the merchant you just met, so he has the merchant reach for something off a high shelf, giving a second chance for you to see the tattoo as his sleeve pulls back). You shouldn't get infinite chances. At the DM's discretion, he can give multiple chances. If the DM thinks the party absolutely HAS to know something, he can have a roll and if nobody beats the DC, he just gives a hint to the person with the highest roll (e.g. "Terris, as he reaches for the book you notice something that makes you feel very uneasy about this person, but your concentration breaks before you pin down exactly what you saw.")

Perception to find something you know is there

If you have unlimited time/no pressure, this roll can just tell you how long it takes you to find this. If you are under pressure, this can tell you whether or not you find it "in time" or "this turn", as appropriate for the situation. Looking for the hidden switch to open the door in combat, for example, would be a standard action and repeatable. Looking for the switch before the kobolds find the party would be one roll (per character) to see if they find it in time. Looking for the switch after the kobolds have been defeated is just a roll to see how long it takes.

Beyond these, the DM should modify DCs to how difficult the task is. Finding the switch in combat will be difficult, as the character will probably be occupied with dodging crossbow bolts and watching their friends fight for their lives. Finding the switch before the kobolds get there is probably easier, but the characters are probably still eyeing the door and readying spells and looking to make sure there isn't anything coming down the other hall. After combat should be easiest, as the characters have few(er) (life-threatening) distractions.

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I've seen a lot of ways to do this, but my personal favorite is this:

Before the session starts, get everyone's passive Perception (in 3.5E, take 10 on a Spot check)

Whenever the party goes into a room, they automatically see everything that their passive score lets them see, no roll required. (Some small common sense regarding line of sight and such is needed). This encourages players to spend points/training on these skills, since it lets them see things right away.

If a player chooses to search/look around (for something specific, or because they think they're missing something), then they roll. No rerolls unless something circumstances change. (As anyone looking for their car keys knows, if you're not seeing it you're not going to.)

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I would disagree here. If I lose my car keys and fail to find them I would keep searching ... now I might have left them at work in which case I am not going to find them at home. If characters are searching for something they are not sure is there the DM should roll but I dont think a missed skill check should stop them from looking again. – Duncan Oct 4 '12 at 23:38
At that point I'd likely make them take 20 (for a "OK, we're ripping the place apart" search), with the attendant penalties. – Allen Gould Oct 5 '12 at 4:13
heh, like the car keys analogy... – Wyrmwood Jul 19 at 0:07

We use perception checks to notice something. If you miss something and don't know it's there can you keep looking for it? No, unless conditions change you can't reroll. Maybe an assassin is picking you off, you can re-roll when one of your party is shot.

If you are searching for something there is a different roll for that. Looking for a hidden door when you know it is on this wall is searching. Just happening to notice a bit of light coming from the bottom of a hidden door is perception.

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The key thing we do on random encounters is when searching for treasure is that we use perception. You can keep looking as long as you make perception. Fail once and you are done. – Mike Wills Jun 8 '11 at 18:06
This is totally dependent on the version of D&D that's being played. If it's 3.5e, then this answer makes sense. If it's 4e, it doesn't because you'd never roll to see the assassin. The assassin would have to beat your passive perception. But technically noticing and searching are not different rolls. They're different uses for the same skill. – Cthos Jun 8 '11 at 18:08
I know in my 4E games I drop passive perception. It is just one of those things that I think doesn't make sense in terms of the system. I get the based-on-real-life justification for it, but I just don't like it. – Sorcerer Blob Jun 8 '11 at 18:13
We are 3e/3.5e with some mix of 4e and 2e. "We" in this context is our gaming group not necessarily by the published rules. – Mike Wills Jun 8 '11 at 18:20

A "perception check" generally is used to be aware of something valuable or dangerous in time to react appropriately to it.

The 3E derived D20 SRD uses Spot for reactive perception checks.

It's a full round action in 3E to retry a spot check. The wording implies only ONE retry, thus ruling out take 20.

There is no general perception skill in 3E, as spot, search, and sense motive serve as 3 subsets.

Spot (WIS)

Check: The Spot skill is used primarily to detect characters or creatures who are hiding. Typically, Spot is opposed by the Hide check of the creature trying not to be seen. Sometimes a creature isn't intentionally hiding but is still difficult to see, so a successful Spot check is necessary to notice it.

A Spot check result of greater than 20 can generally let the character become aware of an invisible creature near the character (though the character can't actually see it). Spot is also used to detect someone in disguise.

Condition                             Penalty
---------                             -------
Per 10 feet of distance               -1
Spotter distracted                    -5


Retry: the character can make a Spot check every time the character has the opportunity to notice something in a reactive manner. As a full-round action, the character may attempt to spot something that the character failed to spot previously.

[D20 SRD, file: srdskillsii.rtf]

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Perception checks happen in two ways.

1. Passive. You are wandering around and there's something you could spot that you're not specifically searching for - a hiding thief, a smudge on the wall that might spell 'trap'. You get a Perception check to see it, but don't get another one unless circumstances change. Starting an encounter can work like this - a ship is way out on the horizon, you fail Perception, it sails closer enough to change the modifiers, you get another check.

2. Active. You are looking for something actively. This works as normal take 10/take 20 kind of skill checks - you can check as much as you want till you get bored, unless you are under pressure or unless missing the check causes something to happen (triggering a trap, most frequently).

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My assumption has always been that perception checks are a standard 6-second action and that you keep repeating them as long as you're looking for something. This was more clear in 3/3.5e than in 4e because in 3e you were allowed to take 20 on searches; therefore if you wanted to spend two minutes per 5-foot square you could find anything that was there.

I think this is better than solitary perception checks because there really should be a difference between the situations where you are hurriedly searching for something, and the situations where you can take your time and really investigate the space you're searching in. In the real world, nobody would be convinced of the absence of a secret door or whatnot based on a six-second glance; if they suspected a secret door then they'd keep looking for a while.

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I agree with you, but find that in those situations, if the players are going to find the door anyway, I modify my roleplaying of the scene. I don't give it for free, but I don't have them rerolling five times either. – Adriano Varoli Piazza Jun 8 '11 at 19:09

The way I have my group checking Perception is that they are able to each do it once. Based on what they roll I will give them what they see. If they MISS something I do not allow a re-roll unless something in the scene has changed or an affect of the MISS has given them a new opportunity to check. I also have different affects for how they roll. Individually or even for the entire group.

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That's pretty much how my group does it. There is also an understood rule that if you miss you can check again, but only after you level. And that's if you are fortunate enough to revisit that area. – Sorcerer Blob Jun 9 '11 at 1:27
@Sorcerer: I am glad that someone else does what I do ha. I always feel like I am doing this differently than most so it is nice to see that other groups are similar :) – Curtis Miller Jun 9 '11 at 15:45
To me it is a simple "you either see it or you don't." In real life if you don't notice something on your own you have to rely on someone else to point it out. Chances are looking and looking are not really going to change anything. I treat "Knowledge" checks the same way. I justify that as the checks are you/your players racking their brains for information and if they don't know it/can't remember they are not going to in their current state. Now once they level it's different, maybe they are smarter or more perceptive due to experience and garner another shot at it. – Sorcerer Blob Jun 9 '11 at 16:53
@Sorcerer: Very good points. Agree with all of it. – Curtis Miller Jun 9 '11 at 17:00